Results of Alternate Usage of Apistan Strips and Formic Acid for Mite Control in Honeybee Colonies

Final Report for FNC98-230

Project Type: Farmer/Rancher
Funds awarded in 1998: $4,951.00
Projected End Date: 12/31/2000
Region: North Central
State: Missouri
Project Coordinator:
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Project Information


The Hawthorne farm is owned by Jim and Kathy Hawthorne and is located 5 miles southwest of Rayville, Missouri. The farm covers 55 acres of which 16 acres are treed; the balance was in the CRP until September 1998. Prior to entering the CRP, the farm produced sorghum, corn and soybeans n crop rotations. The depressed prices of these products coupled with the high risk of soil erosion posed by continuous cropping have meant that it is not cost effective to grow those products any longer. We are looking at alternative methods of agriculture to sustain the family on the farm.

We have been raising bees and expanding the operation for the past three years and currently have just over 100 colonies. We extract, process and market our honey under the “Hawthorne’s Old-fashioned Honey” label.

Future plans call for cultivating our own berries and marketing value added honey products which will incorporate the berries. Future products are strawberry, raspberry and blackberry flavored honey and whipped honey. We pride ourselves in producing a pure, naturally processed product that not only tastes good but also is good for you. Our honey products must maintain the highest standards possible; therefore, we will never become so large a producer that compromising methods are used to speed up the processes.

Currently we are raising 25 pullets and 50 meat birds, we want to see if it is profitable to raise free range chickens and eggs.

We are also researching the possibility of raising Kahtadin sheep on our improved grass and clover pastures on a small scale.

In the summer of 1999, Jim quit his corporate job. This was the first step in our plan to have the farm sustain the family by April 2003.

The objective of this project was to evaluate the success of alternating the use of Formic acid and Apistan (tau-fluvalinate) insecticide strips for control of Verroa Mites (Verroa-Jacobsoni) in honeybee colonies.

I determined at the onset of this project that my experiment would be deemed to be successful if:
1) The Formic Acid Experimental Colonies showed at least equal Verroa mite control to the colonies treated with Apistan both spring and fall. This was proven to be true; the ether test showed slightly better results for the Formic acid.
2) The average honey production in the experimental hives was at least equal to the control hives. This was proven to be true. The average amount of honey harvested for the experimental hives was 58 lbs and the average amount of honey in the control was 59 lbs.
3) There was no increase in winter mortality rate among the experimental colonies compared to the control colonies. The winter mortality was higher in the experimental colonies than it was in the control colonies.
a. Formic Acid Experimental Colonies loss = 13
b. Control Colonies loss = 1

4) Valuable quantitative data gathered during the experiment can be shared with other apiarists. All the data to date is available to others and was shared at the Spring SPAN (Sustaining People through Agriculture Network) conference. I have submitted my report to be published in the Newsletters of the Missouri Beekeepers Association, the Nebraska Beekeepers Association, the Northeast Beekeepers Association, and the Kansas Beekeepers Association. I will also submit my paper to ATTRA, AgEBB and MAC.
5) Procedures for safely handling formic acid can be disseminated amongst local beekeepers. This information has been documented and will be included in all reports.

Short Summary of Process:
Originally we had planned to use the Formic acid in the spring and the Apistan in the fall. We had planned to use very small, inexpensive computer CPU fans run by batteries to move the Formic acid in the colonies. Because we inserted the formic acid in late August and September when the daily temperature was high enough so that the formic acid evaporated at a good rate and moved well within the hives, we found that the fans were not necessary.

Finding the formic acid proved to be extremely difficult. Although formic acid is a product commonly used to make industrial cleaners, there are no producers of those products in the Kansas City area. We have Dr. Marion Ellis, of the University of Nebraska, to thank for finding the formic acid we used. Dr. Ellis had done experiments with formic acid and had an applicator for safely measuring and applying it. He allowed us the use of this applicator for safely measuring and applying it. He allowed us the use of this applicator for our experiment. I would advise anyone applying formic acid to use an applicator designed especially for measuring caustic liquids. Although the formic acid itself was less expensive than anticipated, the trip to Nebraska to pick it up was an unplanned expense.

Throughout the experiment I solicited advice from many people including Dr. Marion Ellis, University of Nebraska; Dr. Marla Spivak, University of Minnesota; Mahmoud Ali, Visiting Scientist, University of Nebraska; and Gerald Hund, commercial producer/packer of “Northland Honey”. In September Jim and I attended “Apinondia”, The World Beekeeping Conference. Here we discussed our experiment with numerous educators from all over the world who had done experiments with formic acid to kill the Verroa mite. Their experiences were enlightening and we gathered much information that we applied in our experiment.

The 50 hives used for the experiment were put together in April of 1999. These were either purchased or split from existing hives but all were built from a 4 frame nucs (three frames of brood and 1 frame of honey). Each colony was contained in one 9 5/8” hive box and kept in this one box hive until the hives were moved to their summer locations. At this time another 9 5/8” box containing 10 empty brood frames was put on each of the hives. We gave each hive one gallon of sugar syrup to help them build up their numbers quickly.

Each hive was checked every tow weeks. During these visits our main objective was to see if the queen was alive and laying, detect any disease present, and to see if the colony was weak or overcrowded. If the queen was damaged or not laying she was replaced. During the course of the experiment we replaced 10 queens. If a hive was found to be weak or diseased we returned the hive to the farm for close observation. Diseased colonies were then medicated and weak colonies re-queened or combined with another stronger colony. If a colony was overcrowded or showed swarming signs we gave them a box (honey super) to store more honey in. swarming occurs in the spring and summer when the colony is gathering honey and the queen is laying lots of eggs to build up the number of bees in the colony.

When a colony becomes over crowded worker bees begin making new queens in queen cells. The old queen will leave to set up a new colony and with her she takes the better portion of the bees. The queen will hatch soon after the old queen leaves. The new queens will mate and begin to lay eggs within two weeks. This phenomenon is the bee’s natural way of reproducing colonies.

Each hive had two Apistan strips inserted early April. The Apistan strips were removed 6 to 7 weeks later and the hives were taken to their summer locations.

The 25 formic acid experimental colonies were taken to ‘Nature Choice’ Farm in St. Joseph, Missouri. Fred and Helen Messner who grow organic fruits and vegetables own Nature’s Choice Farm.

The 25 hives used as the control group were kept at the Clark farm in Independence, Missouri. We had kept 6 hives at the Clark farm for two years prior to the experiment and had very good honey results.

All of the colonies in both yards built up their numbers of bees by early June. We did not split any of these colonies after they were set at their summer locations. We visited the hives every two weeks throughout the season adding honey supers as needed. We extracted honey from the hives in mid July and in late August. The experimental hives had an average of one pound less honey per hive than the control hives at harvest, but this was attributed to the dry spring weather in St. Joseph. In fact, July and August were extremely dry and a lot of the usual flowers were short lived or did not bloom at all in some of our yards. The total average honey harvest per hive was down slightly from past years.

In August after we had taken the last of the honey to be harvested we began the insertion of the formic acid. Before we inserted any formic acid, a mite count was done on each hive. Mites were counted by doing an either test which consist of collecting ~300 bees in a clear container and spraying these bees with starting fluid (ether). This of course killed the bees and the mites. The mites are released from the carrier bees and cling to the sides of the container where they can be counted.

Frames were built that held a shop towel pad between two screens so that the bees could not reach the shop towel to remove it. The formic acid was applied at the rate of 2 ml per full frames of bees in the brood boxes; for example, 12 full frames of bees would receive an application of 24 ml of formic acid. The formic acid was then measured and spread evenly onto the shop towel pad. The frame was inserted into the hive between the two 9 5/8 hive bodies. This was repeated two more times for each hive 10 to 14 days apart. Mites were again counted.

Safety equipment (rubber gloves, eye protection, and an air filtration device) was worn every time the formic acid was used. Careful observations were recorded, noting any unusual behavior by the bees.

The hives continued to be checked every two weeks. The shop towels used to hold the evaporating formic acid were covered with hundreds of mites that had fallen from the bees in the upper hive box. Six of the experimental colonies were considerably weaker in numbers than the others after the last insertion; these colonies had much higher initial mite counts than did the other colonies and probably were damaged to the point where they would have died during the winter months. Two to four Apistan strips were inserted into every control hive. These were removed seven weeks later. All the hives were fed two gallons of sugar syrup in November to help them build up their food supply for the winter. At the last check prior to the onset of winter, on December 3, 1999, one week experimental colony was found to have suffered a queen loss and it was combined with a stronger colony.

The colonies were all checked on February 21, 2000. It was an unusually warm day for February and Jim and I took advantage of the weather. Although it appeared in December that all was well, we found 10 of the formic acid experimental colonies dead. We found one control colony dead.

On March 27 all the colonies were checked again. All of the control colonies were doing well. The formic acid colonies had lost another 3 and 3 more were found to be very weak in numbers

In my final analysis, I can’t say that the experiment was a success because the winter mortality rate was over 50% for the formic acid experimental colonies and only 4% for the control colonies.

The conclusions that I have come to are:
1) Under the conditions of the experiment formic acid causes damage to the colonies.
2) Since the number of bees were on the average the same for both groups; I have to conclude that the Queens were damaged during the insertion of the formic acid. This caused the Queens to die from the stress of the cold during the winter months or the Queens were rejected because they were damaged and could not lay eggs. The bees from those colonies may have migrated to one of the other healthy colonies.

Will I use formic acid again? Yes, I will use it again this fall on the same colonies but I will replace any Queens that are not laying before the onset of winter.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.